Diaphragm plate construction



H. M. HOEKSTRA Filed March 16. 1961 JZrc-s. 5.

' INVENTOR. l/[RMJN M l/MKSTM A T TORIJEY V United States Patent Thepresent invention relates as indicated to a novel diaphragm plateconstruction and more particularly to a diaphragm plate construction fora fluid pressure servomotor wherein novel means are provided forretaining the control valve mechanism in the diaphragm plate.

An object of the present invention is the provision of a simplifiedconstruction of a diaphragm plate for a fluid pressure motor in whichinternal parts are retained in position by a radially extending pin thatis held in place by means of the power diaphragm.

A further object of the present invention is the provision of a new andimproved diaphragm plate construction for a fluid pressure servomotor inwhich the diaphragm plate has an axially extending valve chamber whichopens outwardly at one side of the diaphragm plate and into which thevarious valve elements are placed-this structure further including aretainer member for the valve elements which is slid into a radialopening in the diaphragm plate to project into the valve elements andhold them in position, and the retainer member being adapted to be heldin position by an annular power diaphragm which is snapped over theretainer member.

The invention resides in certain constructions and combinations andarrangements of parts; and further objects and advantages of theinvention will become apparent to those skilled in the art to which theinvention relates from the following description of the preferredembodiment described with reference to the accompanying drawings forminga part of this specification, and in which:

FIGURE 1 is a cross sectional view of fluid pressure servomotorembodying principles of the present invention;

FIGURE 2. is a fragmentary cross sectional view through a portion of thediaphragm plate seen in FIG- URE l; and

FIGURE 3 is a plan view of a key or stop member shown in FIGURE 1.

The shell or housing of the servomotor shown in the drawings is formedby means of a cup-shaped front housing section and a rear cover section12 which is slid into the open end of the front section and suitablyheld in place to provide an enclosure for its axially extending internalchamber. The internal chamber of the servomotor is divided into frontand rear opposing power chambers 14 and 16 respectively by means of adiaphragm 18the radially outer portion of which is suitably clampedbetween the housing sections, and the radially inner portion of which issealingly affixed to a diaphragm plate 20. 'In the preferred embodimentshown in the drawing, the diaphragm plate 20 is made in one integralplastic piece having a rearwardly extending cylindrically formed boss 22which projects out through an opening in the rear cover plate 12 for thepurpose of providing a sliding vacuum type seal with respect to thecover plate 12. The sliding vacuum seal may be formed in any suitablemanner, and as shown in the drawing, is formed by a U-packing 24 that isseated up against a stamped shoulder 26 in the cover plate 12. TheU-packing 24 is held in place by means of an annular spaldite washer28-which in turn is held in place by means of an annular metal ring 30having interference fit with respect to the sidewalls of the stampedcylindrical section 32 of the cover plate 12. A corrugated rubber boot34 is suitably lice afiixed between the outer end of the cylinder boss22 and the outer end of the stamped cylindrical section 32 of the coverplate 12 to provide a suitable dirt seal for the sliding sealing outersurfaces of the cylinder boss 22.

The diaphragm plate 20 is further provided with a radially extendingintegral flange 36 for the purpose of supporting the center section ofthe diaphragm 18; and inasmuch as the diaphragm shown is of the curtaintype, the periphery of the integral flange 36 is turned forwardly as at3 8 so that the diaphragm 18 will lay up against the periphery of theturned portion 38 in the manner customary for curtain diaphragmstructures. The radially inner portion of the diaphragm 18 has a centralopening 40 therethrough of a diameter which will slip or pass over theannular boss 22. The diaphragm plate 20 is of course thickened at thejuncture of the cylindrical boss 22 and the integral flange 36; and asuitable diaphragm receiving groove 42 is provided in this thickenedportion adjacent the rear surface of the integral flange 36 to provide aseat into which the diaphragm 18 may be snapped. The diaphragm 18 may beprovided with rubber bumpers 44, and a thickened annular portion 46, asexplained in the Maxwell L. Cripe application Serial No. 75,596; so thatonce the diaphragm is seated in position in the groove 42, a vacuum typeseal will automatically be provided between the diaphragm l8 and thediaphragm plate 20.

The servomotor shown in the drawing is of the type which is intended tobe used for the power actuation of a conventional master cylinder of anautomotive hydraulic braking system; so that the front end of the shell10 is adapted to be bolted directly to the rear end of the mastercylinder in a manner providing a vacuum tight seal. The diaphragm plate20 is provided with an axially extending opening 48 which extends fromthe front surface of the diaphragm plate 20 through the cylindrical boss22; and the front end of the opening 48 is enlarged as at 50 to receivethe headed end 52 of a push rod 54 which abuts and drives the hydraulicpiston of the master cylinder, not shown.

In the fluid pressure motor construction shown in the drawing, vacuum iscontinually supplied to the front opposing power chamber ]l4 through atubular check valve structure 56; and the diaphragm plate 20 is causedto be biased into the position shown in the drawing by the piston returnspring 58 whenever vacuum is also admitted to the rear opposing powerchamber 16. A block of elastomeric material 60 is provided between theheaded end 52 of the push rod 54 and the bottom of the enlarged sectionso of the axially extending opening 48, for the purpose of resilientlytransmitting force from the diaphragm plate 2!} to the push rod 54, asis explained more fully in the above referred to Maxwell L. Cripeapplication.

The structure so far described will have utility in various types offluid pressure motors. Power output of the fluid pressure motor is ofcourse regulated by controlling the pressure in the rear opposing powerchamber 16; and inasmuch as the motor shown in the drawing is a servo.-motor, the control valve structure is mounted in, and carried by thediaphragm plate 20. In the servomotor construction shown in the drawing,the control valve structure is very conveniently and simply constructedby a. plurality of stacked elements which are installed upon the controlrod 62and after which, the assembly is completed by inserting theassembled stacked elements into the rear end of the central opening 48in the cylindrical boss 22.

The elements which are assembled upon the push rod 62 generally comprisea control member 64 having a rearwardly facing annular atmospheric valveseat 66 thereon for sealing abutment with a flexible annular rubberpoppet member 68. The annular rubber poppet member 68 is suitablystifiened by an annular metal washer '70 about which the rubber ismolded, and the poppet member 68 further includes an integral flexiblediaphragm portion 72 having a radial outer periphery which is suitablythickened for sealing engagement with the sidewalls of the axial opening48 in the cylindrical boss 22. The rubber poppet member 68 is biased upagainst the atmospheric valve seat 66 by a coil spring 76 that isinterpositioned between the rod 62 and a flanged tube 78 which is fittedinto the inside of the annular poppet member 68 in abutment with itsstiffening washer '70. The valve structure is caused to assume thenormal servomotor deactuating position shown in the drawing by a. valvereturn spring 30 which is interpositioned between the push rod 62 and asealing washer 82 which biases the outer thickened portion 74 of thepoppet diaphragm 72 into sealing engagement with the sidewalls of theopening 46. A suitable shoulder 84 is provided on the push rod 62 forreceiving a spring retainer 86 against which the valve return spring 80is positioned.

The opening 48 through the diaphragm plate 20 is provided with aplurality of gradually increasing diameter sections proceeding from itssmallest portion adjacent the reaction disc 60 to the rear opened end ofthe cylindrical boss 22 so that all of the parts which are assembledupon the push rod 62 can he slid into position. The previouslyenumerated valve parts will be assembled on the push rod 62 in generallythe reverse order given above; and after the control member 64 is placedover the ball end of the push rod 62, it is suitably stacked in positionas at 88. The vacuum valve seat 90 for the control valve structure isprovided by a. shoulder formed by increasing the diameter 48 at aposition generally opposite to the assembled position of atmosphericvalve seat 66; so that a small annular control pressure area existsbetween the two valve seats 66 and 90. This control pressure area 92extends around the control member 64 and is communicated to the rearopposing power chamber 16 by means of the control passage 94. The outerperiphery of the poppet member 68 is of course adapted to seat againstthe vacuum valve seat 90; and the central opening 48 is further enlargedat a point rearwardly of the vacuum valve seat 90 to provide a suitableshoulder 96 against which the outer thickened portion '74 of the poppetmember can be biased to assure a vacuum type seal with respect to thesidewalls of the opening 48. Vacuum is continually communicated to theannular area between the shoulders 90 and 96 and radially outwardly ofpoppet member 68 by means of the vacuum passage 98 which is cast in thediaphragm plate 20 to at all times communicate with the front opposingpower chamber 14.

It will now be seen that atmospheric pressure continually communicatesto the area inside of the flexible poppet member 68 from the right handopen end of the opening 48 in the cylindrical boss 22. In the positionshown in the drawing, the atmospheric valve seat 66 sealingly abuts thepoppet member 68; so that atmospheric pressure is isolated from the rearopposing power chamber 16 of the servomotor. It has further beenexplained that the valve spring 80 biases the push rod 62 rearwardlywith sutficient force to hold the atmospheric valve seat 66 against thepoppet member 68, and in turn hold the poppet member 68 away from thevacuum valve seat 96. In this condition of the control valve structure,vacuum from the front opposing power chamber 14 flows through passage 93to the control area 22, and passage 94, to the rear opposing powerchamber 16. When it is desired to actuate the servomotor, the push rod62 is pushed forwardly to a point where the poppet member 68 abuts thevacuum valve seat 90 to isolate the vacuum submerged front opposingpower chamber 14 from the rear opposing power chamber 16-after whichtime a slight further movement of the push rod 62 moves the atmosphericvalve seat 66 out of engagement with the poppet member 68 to permit airpressure to flow past the atmospheric valve seat 66 and into the rearopposing power chamber 16. Pressure in the rear opposing power chamber16 biases the diaphragm 20 firmly up against the flange 36 of thediaphragm plate 20 to assure positive sealing engagement therewith, andthereafter transmit force to the diaphragm plate to drive the push rod54 forwardly into the master cylinder.

The forward end of the control member 64 has a close sliding fit in thesmall diameter section of the opening 48 and is normally held out ofengagement with the elastomeric disc 60. After a differential pressureis established across the diaphragm 18 and force is applied to the pushrod 54, a suflicient squeezing of the elastomeric disc 60 takes place tocause it to flow up against the front face of the control member 64 andprovide a reaction which opposes the valve opening movement on the pushrod 62. This functioning is generally described in considerable detailin the above referred to Maxwell L. Cripe application, and so will notnow be further elaborated upon. After the desired braking effort isachieved, forward movement of the control rod 62 is stopped-followingwhich the diaphragm plate 20 moves forward a slight additional amount tobring the poppet member 68 into engagement with the atmospheric valveseat 66, and thereby preventing further flow of air to power chamber 16.

When it is desired to reduce the force generated by the servomotor, theforce applied to the control rod 62 is reduced; whereupon the pressureof the elastomeric disc 60 along with the force of the return springtit) causes the control member 64 to bias the poppet member 68 out ofengagement with the vacuum valve seat and so reduce the pressure in therear opposing power chamber 16. Complete removal of force on the controlrod 62 permits the valve parts to assume the position shown in thedrawing, and a vacuum established in the rear opposing power chamber 16of the same intensity as exists in the front opposing power chamber 14.

It will be seen that the servomotor construction so far described is theepitomy of simplicity. As has been previously explained, the entireassembly of the control valve structure is accomplished by stackingelements upon the push rod 62, and thereafter inserting the entire valveassembly into its receiving bore to automatically provide all of itsnecessary sealing, guiding and reaction producing engagements.

According to principles of the present invention, the diaphragm plate 20is proportioned so that the rear surface of the radial flange 36 fallsradially outwardly of the control member 64. A radially inwardlyextending opening or slot 100 is cast between the bottom of the groove42 and the surfaces of the control member 64; and an annular groove 102is formed in the surface of the control member 64 to receive a stop pinor abutment member 104. The groove 102 in the control member 64 isprovided with suflicient axial width to accommodate all necessary valvetravel; and the forward face of the groove 102 is so positioned as toprovide the desired valve return or release position wherein the frontface of the control member 64 is out of engagement with the elastomericdisc 60, and the desired clearance provided between the vacuum valveseat and the poppet member 68. After the valve assembly has beeninstalled upon the rod 62 and the assembly pushed into position, the pin104 is inserted into the slot 100. The diaphragm 18 is thereaftersnapped into its sealing position to automatically hold the stop pin 104in its receiving opening 100. The pin 104 is of course provided withsufficient length so that its inner end extends into the groove 102 whenits outer end is resiliently engaged by the thickened portion 46 of thediaphragm 13. It will thereby be seen that the entire assembly isaccomplished by simply snapping the various parts together; and that thediaphragm 18 not only provides the function of affecting a seal betweenthe chambers 14 and 16, but retains the stop pin 1M in position to holdthe entire assembly together.

It will be apparent that objects heretofore enumerated as well as othershave been accomplished, and that there has been provided a fluidpressure motor construction of the type using a power diaphragm whereinthe diaphragm, when snapped into sealing position, is used to retaininternal parts in their assembled positions.

While the objects and advantages of the invention have beenaccomplished, I do not wish to be limited to the particular constructionshown and described; it is my intention to cover hereby all noveladaptations, modifications and arrangements thereof which come withinthe practice of those skilled in the art to which the invention relates.

I claim:

1. In a fluid pressure motor: a housing having an axially extendingchamber therein, a diaphragm plate in said chamber, said diaphragm platehaving an internal chamber therein and a radially inwardly extendinggroove in its external surface, said diaphragm plate having a radiallyextending opening extending between said groove and its internalchamber, a pin positioned in said radially extending opening, and anannular diaphragm having a central opening with its radially innerportion surrounding its central opening snapped into said groove toretain said pin.

2. In a fluid pressure servomotor: a housing having an axially extendingchamber therein, a diaphragm plate in said chamber, said diaphragm platehaving an axially extending internal chamber therein and a radiallyinwardly extending groove in its external surface, said diaphragm platehaving a radially extending opening extending between said groove andits internal chamber, an axially movable member in said internal chamberof said dia phragm plate, said axially movable member having a groove inits external surface opposite said radially extending opening of saiddiaphragm plate, a pin positioned in said radially extending opening andextending from the bottom of said groove in said diaphragm plate andinto said groove of said axially movable member, and an annulardiaphragm having a central opening with its radially inner portionsurrounding its central opening snapped into said groove in saiddiaphragm plate to retain said pin and the radially outer portion ofsaid annular diaphragm being sealed to said housing.

3. In a fluid pressure servomotor: a housing having an axially extendingchamber therein, a diaphragm plate in said chamber, said diaphragm platehaving an axially extending internal valve chamber therein and aradially inwardly extending groove in its external surface, saiddiaphragm plate having a radially extending opening extending betweensaid groove and its internal'chamber, said axially extending valvechamber being enlarged at its outer end to form a valve seat shoulder, aflexible annular poppet member having a radially inner portion adaptedto abut said shoulder and a radially outer portion sealed to thesidewall of said valve chamber, a control member in said valve chamberaxially inwardly of said shoulder for abutment with said annular poppetmember, said control member having a groove therein positioned generallyopposite said radial opening, a stop member positioned in said radialopening and extending from said groove in the outer surface of saiddiaphragm plate into said groove of said control member, and an annularflexible diaphragm having a central opening, said diaphragm having aradially outer portion sealed to said housing and a radially innerportion surrounding its central opening slipped into said groove of saiddiaphragm plate to cover and hold said stop member in said radialopening.

4. In a fluid pressure servomotor and the like: a housing having aninternal axially extending chamber therein; a movable wall in saidchamber, said movable wall having a generally cylindrically shaped bossaxially extending through one end of said housing, said boss having anaxially extending internal valve chamber therein which is stepped downin at least two successive stages to provide an inner and an outershoulder facing axially outwardly of said valve chamber, an annularilexibie poppet member having an inner thickened portion for engagingsaid inner shoulder and an outer portion having an interference fit withthe sidewalls of said valve chamber, and an intregal flexible portioninterconnecting said inner and outer portions, a control memberpositioned axially inwardly of said poppet member and having an axiallyoutwardly facing valve seat for engaging said poppet member radiallyinwardly of said inner shoulder and adapted for axial movement tosealingly engage said poppet member and disengage it from said innershoulder, a control rod connected to said control member and projectingaxially outwardly through said annular poppet member, means biasing saidouter portion of said poppet member radially outwardly into sealingengagement with the sidewalls of said valve chamber and axially inwardlyagainst said outer shoulder, and said movable wall having a low pressuresource communicating with said valve chamber between said shoulders, acontrol passage communicating to the portion of said valve chamberinwardly of said inner shoulder, and a higher pressure sourcecommunicating to the outer end of said valve chamber, said movable wallhaving a generally radially extending opening communicating with saidvalve chamber opposite said control member, said control member having arecess therein opposite said radially extending opening, and an abutmentpin positioned in said radially extending opening and extending intosaid recess to prevent withdrawal of said control member and to therebyhold the structure together.

References Cited in the file of this patent UNITED STATES PATENTS2,411,458 Penrose Nov. 19, 1946 2,811,925 Crookston Nov. 5, 19572,834,184 Ingres May 13, 1958 2,949,892 Ayers Aug. 23, 1960 2,976,846Stelzer Mar. 28, 1961

1. IN A FLUID PRESSURE MOTOR: A HOUSING HAVING AN AXIALLY EXTENDINGCHAMBER THEREIN, A DIAPHRAGM PLATE IN SAID CHAMBER, SAID DIAPHRAGM PLATEHAVING AN INTERNAL CHAMBER THEREIN AND A RADIALLY INWARDLY EXTENDINGGROOVE IN ITS EXTERNAL SURFACE, SAID DIAPHRAGM PLATE HAVING A RADIALLYEXTENDING OPENING EXTENDING BETWEEN SAID GROOVE AND ITS INTERNALCHAMBER, A PIN POSITIONED IN SAID RADIALLY EXTENDING OPENING, AND ANANNULAR DIAPHRAGM HAVING A CENTRAL OPENING WITH ITS RADIALLY INNERPORTION SURROUNDING ITS CENTRAL OPENING SNAPPED INTO SAID GROOVE TORETAIN SAID PIN.